Field of the Invention
The present invention relates to an optical apparatus that receives light reflected from a target portion when the target portion is irradiated with the light and also relates to an image forming apparatus, such as a copying machine, a printer, or a facsimile machine, which includes the optical apparatus.
Description of the Related Art
In general, an image forming apparatus is sensitive to an operating environment and various conditions (e.g., the number of sheets to be printed) because the density of each color is variable and the tint of a formed image is variable too. A color image forming apparatus is configured to overlap a plurality of color images to form a composite color image. Therefore, positional deviation tends to occur in respective color images. For example, when the color image forming apparatus includes four-color (e.g., yellow, magenta, cyan, and black) photosensitive drums, the relative position between two of four-color images is variable.
There is a conventional method for correcting the positional deviation of each color or each color density. More specifically, the conventional method includes causing a light-receiving member of an optical apparatus to detect the amount of light reflected from a patch (i.e., a reference pattern) formed on an intermediate transfer member, a photosensitive member, or a sheet. The method includes calculating a positional deviation between respective colors and a density variation of each color based on a detection result representing the amount of received light. The method includes controlling various image forming conditions based on the calculation result in such a way as to appropriately adjust the positional deviation between respective colors and the density of each color.
As discussed in Japanese Patent Application Laid-Open No. 2013-191835, there is a conventionally known configuration capable of improving the detection accuracy of an optical apparatus (e.g., an optical sensor) that is used in the above-mentioned patch detection.
The optical apparatus discussed in Japanese Patent Application Laid-Open No. 2013-191835 includes a light-emitting member and a light-receiving member mounted on a substrate and covered with a housing that serves as a light-shielding member. However, according to such a conventional arrangement, the detection accuracy may deteriorate due to stray light. Therefore, the present invention intends to prevent the detection accuracy from being deteriorated by the stray light.